Do you expect bitcoin and other cryptocurrencies to go down in price ? As people will swtich to hard cash or gold?
Note : There are wide power outages, servers getting down, no electrictiy and everything bad you can expect if WW3 happens
I agree with you that the most important thing during a world war is safety kits, survival kits, food, shelter and weapons to protect ourselves. If all countries in the world will join the war then currency will lost its value. After all life and survival is most important than economics. The only way to make currency retain its value is to avoid a world war at any cost.
Let's also mention that when a world war happens for sure most currencies will turn to shit and no one would trade money for whatever goods they are holding. Everything will shutdown and nothing in the world will be stable. Especially, this will affect those countries that are part of the conflict, the true warring countries or nations.